This invention relates to the field of submergible floating vessels, particularly floating dry docks and barges. In particular, this invention relates to a new type of submergible floating dry dock or barge and a method for using same which is especially well adapted for use both in very shallow bodies of water and in the open ocean and which is simple and economical in both construction and operation.
Submergible floating dry docks have been in use for many years. Such dry docks operate by the use of flotation chambers which are flooded with water to submerge the dock. Air is then introduced into these chambers to displace the water therefrom, thereby raising the dock and the vessel held within its hold. Various mechanisms have been devised to achieve the submersion and flotation functions of such a dry dock. However, the typical floating dry dock requires the use of flotation chambers underlying the deck or platform of the hold as well as along the sides of the hold. Such a construction results in a structure which extends several feet below the deck or platform, and thus such dry docks can only be used in water which is sufficiently deep to accommodate the entire depth of this sub-deck structure. Therefore, the use of such dry docks is precluded in many of the shallow bays and inlets where many marinas for small, relatively shallow-draft pleasure craft are located. Also, the substantial thickness of the bottom structure in such dry docks makes them difficult to use in salvage operations where, for example, it is necessary to raise a vessel which is resting on the bottom of a body of water. This difficulty arises from the necessity to lift the sunken vessel vertically several feet so as to clear the underdeck flotation structure of the dry dock. Furthermore, because the ballast in such dry docks is located under the load, the shifting of the ballast under the load due to, for example, rough weather conditions, can produce a severe instability which may result in capsizing. The same problem is present in conventional submergible barges.